Greyish mold on TOMATOES only
Some tomatoes only (not leaves) have greyish mold on them. Usually on lower branches. And only on three of the fifteen plants and not all tomatoes on each plant is affected.
There are so many possible diseases of tomatoes (see this article): https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-diseases.htm
the only reliable way to identify what you're describing would be to take some samples to the nearest Extension Service. This link will help you locate one: https://www.gardeningknowhow.com/extension-search/